Method and apparatus for closing tubes

Abstract

A bottom in a tube having an open end is formed by heating the tube and a supporting mandrel and advancing a sleeve over the end of the tube which flares outwardly after heating so as to collapse the flared end. The collapsed end of the tube is closed by contacting the collapsed end with a mold which cooperates with the sleeve to form the bottom.

What is claimed is: 
     
       1. A method of manufacturing a plastic tube having a bottom formed from an open-ended tube without using additional material for forming the bottom comprising the following steps: supporting the open-ended tube on a mandrel extending longitudinally into said tube;   heating said mandrel and said tube simultaneously so as to flare the end of the open-ended tube outwardly away from the heated mandrel;   collapsing said flared end by contact with a sleeve surrounding said open-ended tube and said mandrel and telescopically movable relative thereto;   heating said mandrel and said tubes while collapsing said flared end;   closing said collapsed, previously flared end to form said bottom by contacting said collapsed end with a mold which is substantially cooler in temperature than said mandrel and forming said bottom over the end of said mandrel;   separating said mold from said formed bottom and said mandrel; and   separating said mandrel from said tube after said mold has been separated from said bottom and said mandrel.   
     
     
       2. The method of claim 1 wherein said mandrel and said open-ended tube are heated radiantly. 
     
     
       3. The method of claim 2 wherein said mandrel and said open-ended tube are heated radiantly from a source located adjacent said mandrel end. 
     
     
       4. The method of claim 1 wherein said tube and said mandrel are heated substantially longer than said mold contacts said collapsed end of said tube. 
     
     
       5. The method of claim 1 wherein said sleeve is heated simultaneously with said mandrel and said open-ended tube. 
     
     
       6. The method of claim 5 wherein said mandrel, said sleeve, and said open-ended tube are heated radiantly from a source located adjacent said mandrel end. 
     
     
       7. The method of claim 1 wherein the open end of said tube opposite said collapsed end rests on a shoulder of said mandrel. 
     
     
       8. The method of claim 1 wherein said mold resiliently contacts said collapsed end. 
     
     
       9. The method of claim 8 wherein the open end of said tube opposite said collapsed end rests on a shoulder of said mandrel. 
     
     
       10. The method of claim 9 wherein said mandrel and said open-ended tube are heated radiantly from a source located adjacent said mandrel end. 
     
     
       11. The method of claim 1 further comprising the step of cooling said mandrel while closing said collapsed end. 
     
     
       12. The method of claim 1 wherein a plurality of said open-ended tubes are simultaneously supported by a plurality of mandrels respectively. 
     
     
       13. The method of claim 12 wherein said open-ended tubes on said mandrels are sequentially heated and closed. 
     
     
       14. The method of claim 13 wherein said tubes are heated and collapsed prior to closing. 
     
     
       15. The method of claim 14 wherein said open-ended tubes on said mandrels are simultaneously heated, simultaneously heated and collapsed and simultaneously closed. 
     
     
       16. A method of manufacturing a plastic tube having a bottom formed from an open-ended tube without using additional material for forming the bottom comprising the following steps: heating the open-ended tube so as to flare the end outwardly;   collapsing the flared end;   closing the collapsed, previously flared end to form said bottom against a heated molding surface located on the interior of the tube; and   further heating the end after flaring and before closing.   
     
     
       17. The method of claim 16 wherein the temperature of said molding surface is controlled. 
     
     
       18. The method of claim 16 wherein the bottom is also formed against a mold located on the exterior of the tube. 
     
     
       19. The method of claim 18 wherein the temperature of the mold on the exterior is controlled independently from the temperature of the molding surface on the interior. 
     
     
       20. A method of manufacturing a plastic tube having a bottom formed from an open-ended tube without using additional material for forming the bottom comprising the following steps: supporting the open-ended tube between a mandrel and a sleeve;   heating said mandrel, said sleeve and said tube simultaneously so as to flare the end of the open-ended tube outwardly away from the heated mandrel with the end of the mandrel being separated from the end of said sleeve a distance substantially less than the maximum cross-sectional dimension of the tube;   collapsing said flared end by contact with said sleeve surrounding said open-ended tube and said mandrel and being telescopically movable relative thereto;   closing said collapsed, previously flared end to form said bottom by contacting said collapsed end with a mold;   separating said mold from said formed bottom and said mandrel; and   separating said mandrel from said tube after said mold has been separated from said bottom and said mandrel.   
     
     
       21. The method of claim 20 wherein substantial contact between the flared end and the sleeve is avoided. 
     
     
       22. The method of claim 20 wherein the tube is flared outwardly a distance substantially greater than the thickness of the sleeve. 
     
     
       23. The method of claim 20 wherein substantially all of the end of said tube extending beyond said mandrel and said sleeve is flared outwardly. 
     
     
       24. The method of claim 20 wherein said mandrel is at least partially cylindrical and the end of said sleeve is substantially aligned with the end of the cylindrical portion of said mandrel. 
     
     
       25. A method of manufacturing a plastic tube having a bottom formed from an open ended tube without using additional material for forming the bottom comprising the following steps: supporting the open ended tube between a mandrel and a sleeve the end of said sleeve being substantially aligned with the end of the cylindrical portion of said mandrel;   heating said mandrel, said sleeve and said tube simultaneously so as to flare the end of the open ended tube outwardly away from the heated mandrel, the tube being flared outwardly a distance substantially greater than the thickness of the sleeve;   collapsing said flared end by contact with said sleeve surrounding said open ended tube and said mandrel said sleeve being telescopically movable relative thereto;   closing said collapsed previously flared end to form said bottom by contacting said collapsed end with a mold;   separating said mold from said formed bottom of said mandrel; and   separating said mandrel from said tube after said mold has been separated from said bottom and said mandrel.   
     
     
       26. The method of claim 25 wherein substantial contact between the flared end and the sleeve is avoided. 
     
     
       27. The method of claim 25 wherein the end of the mandrel is separated from the end of the sleeve during the flaring of said tube a distance substantially less than the maximum cross sectional dimension of the tube. 
     
     
       28. The method of claim 25 wherein substantially all of the end of said tube extending beyond said mandrel and said sleeve is flared outwardly.